Spatial Analysis of Air Velocity, Air Temperature, and Humidity in Natureform Single-Stage Incubators Using Simulated Eggs

Abstract

Spatial variation of the thermal environment within incubators has been a critical concern for the optimal development of egg embryos. Variations in air velocity, temperature, and humidity can alter embryonic mortality, egg moisture loss, hatchability, and post-hatch growth. Researchers are also concerned with minimizing the variation within small research incubators to reduce the within-treatment variation in order to compare thermal treatments. Therefore, the objective of this study was to quantify the spatial variation of air velocity, temperature, and humidity within a single-stage incubator using simulated eggs for both setter-phase incubation (SPI) and hatcher-phase incubation (HPI). Eight small Natureform incubators capable of holding 1080 eggs were used. Air velocity was measured using a hot-wire anemometer at 60 Hz for both SPI and HPI. Two readings, perpendicular and parallel to the mixing fan, were taken at each of 25 locations across six levels. The 25 locations were combined into five zones for comparison. The incubator was set to 37.5 °C and 65 % RH for SPI and 36.7 °C and 60 % RH for HPI for a test period of three days. During SPI, air temperature (16 locations) and relative humidity (2 locations) was measured across six levels with self-contained (iButton) data loggers attached to 3D-printed eggs. During HPI, air temperature (9 locations) and relative humidity (2 locations) was measured across six levels with iButtons attached within wiffle balls attached to chick baskets. Relative humidity was converted to vapor pressure deficit (VPD). The main effects of location and level were analyzed with two-way ANOVA with the GLIMMIX procedure (SAS ver. 9.4) for air velocity, temperature, and humidity. During SPI, mean air velocity by zone was highest near the fan (1.8 m per s) and lowest at the front of the incubators (0.6 m per s). During HPI, mean air velocity was highest outside the chick baskets and lowest within the chick basket. During SPI, mean air temperature ranged between a low of 37.3 °C towards the front to a high of 38.2 °C near the back left corner. During HPI, air temperature ranged between a low of 36.7 °C towards the front, to a high of 37.5 °C near the left and right side of the basket. During SPI, VPD ranged from 2.0 kPa and 2.05 kPa. For HPI, VPD ranged between 1.99 kPa and 2.05 kPa. 3D-printed eggs with iButtons can effectively capture air temperature and relative humidity near the egg surface during incubation. This study characterized air velocity patterns in a Natureform single-stage incubator and provided a methodology to measure temperature and relative humidity variation during research studies involving live embryos.